| // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use std::collections::{HashMap, HashSet}; |
| use std::default::Default; |
| use std::hash::{Hasher, Hash, BuildHasherDefault}; |
| use std::ops::BitXor; |
| |
| pub type FxHashMap<K, V> = HashMap<K, V, BuildHasherDefault<FxHasher>>; |
| pub type FxHashSet<V> = HashSet<V, BuildHasherDefault<FxHasher>>; |
| |
| #[allow(non_snake_case)] |
| pub fn FxHashMap<K: Hash + Eq, V>() -> FxHashMap<K, V> { |
| HashMap::default() |
| } |
| |
| #[allow(non_snake_case)] |
| pub fn FxHashSet<V: Hash + Eq>() -> FxHashSet<V> { |
| HashSet::default() |
| } |
| |
| /// A speedy hash algorithm for use within rustc. The hashmap in liballoc |
| /// by default uses SipHash which isn't quite as speedy as we want. In the |
| /// compiler we're not really worried about DOS attempts, so we use a fast |
| /// non-cryptographic hash. |
| /// |
| /// This is the same as the algorithm used by Firefox -- which is a homespun |
| /// one not based on any widely-known algorithm -- though modified to produce |
| /// 64-bit hash values instead of 32-bit hash values. It consistently |
| /// out-performs an FNV-based hash within rustc itself -- the collision rate is |
| /// similar or slightly worse than FNV, but the speed of the hash function |
| /// itself is much higher because it works on up to 8 bytes at a time. |
| pub struct FxHasher { |
| hash: usize |
| } |
| |
| #[cfg(target_pointer_width = "32")] |
| const K: usize = 0x9e3779b9; |
| #[cfg(target_pointer_width = "64")] |
| const K: usize = 0x517cc1b727220a95; |
| |
| impl Default for FxHasher { |
| #[inline] |
| fn default() -> FxHasher { |
| FxHasher { hash: 0 } |
| } |
| } |
| |
| impl FxHasher { |
| #[inline] |
| fn add_to_hash(&mut self, i: usize) { |
| self.hash = self.hash.rotate_left(5).bitxor(i).wrapping_mul(K); |
| } |
| } |
| |
| impl Hasher for FxHasher { |
| #[inline] |
| fn write(&mut self, bytes: &[u8]) { |
| for byte in bytes { |
| let i = *byte; |
| self.add_to_hash(i as usize); |
| } |
| } |
| |
| #[inline] |
| fn write_u8(&mut self, i: u8) { |
| self.add_to_hash(i as usize); |
| } |
| |
| #[inline] |
| fn write_u16(&mut self, i: u16) { |
| self.add_to_hash(i as usize); |
| } |
| |
| #[inline] |
| fn write_u32(&mut self, i: u32) { |
| self.add_to_hash(i as usize); |
| } |
| |
| #[cfg(target_pointer_width = "32")] |
| #[inline] |
| fn write_u64(&mut self, i: u64) { |
| self.add_to_hash(i as usize); |
| self.add_to_hash((i >> 32) as usize); |
| } |
| |
| #[cfg(target_pointer_width = "64")] |
| #[inline] |
| fn write_u64(&mut self, i: u64) { |
| self.add_to_hash(i as usize); |
| } |
| |
| #[inline] |
| fn write_usize(&mut self, i: usize) { |
| self.add_to_hash(i); |
| } |
| |
| #[inline] |
| fn finish(&self) -> u64 { |
| self.hash as u64 |
| } |
| } |